1. Field of the Invention
The present invention relates to an improvement in reducing the energy requirement for dehumidifying air by providing a unitary housing which forces flowing air to be redirected for exhaust in a direction 180.degree. from the intake direction of the airflow, and which allows a regenerative heat exchange between the intake and exhaust airstreams of an air cooling system. The invention further relates to the combination of the aforementioned heat exchanger with one or more dampers to permit selective variation of the degree of regenerative heat exchange, and therefore the degree to which the present invention provides (a) cooling, (b) dehumidification, (c) a selectable combination of cooling and dehumidifying of air being conditioned in the unit, and (d) a bypass capability whereby the regenerative heat exchange and cooling functions are bypassed.
2. Discussion of the Prior Art
Air conditioning requires relatively large amounts of energy to provide comfortable ambient indoor air under a variety of weather conditions, depending upon the climate and the season. Devices that cool and dehumidify air are well known, whereby, as the air is cooled, moisture condenses out of the air resulting in cooler, drier air being returned to the atmosphere. For the design of a dehumidifying heat exchanger, an important question is whether, and how much, heating will be applied to the air after it has been cooled for the purpose of dehumidifying it. If the cooled, and thus dehumidified air is simply exhausted into the ambient indoor space without further heating, the process is one of traditional air conditioning. However, if after dehumidification, the air is reheated before being exhausted into the ambient space, the process will be one of traditional dehumidification.
In the traditional air conditioning system, the cooling coil is controlled by ambient temperature alone, and not by ambient humidity. Thus, when ambient air rises to the temperature for which a thermostat is set, the air conditioner will engage until it is shut down by the thermostat. Temperature, and not humidity of ambient air, is the controlling factor. Similarly, traditional dehumidification is controlled by ambient humidity alone. The unit is engaged and shut down on the criterion of humidity alone.
In the prior art, there exists a number of heat exchangers utilizing a regenerative type of heat exchange airflow in which air is forced through the housing in intake channels and then redirected 180.degree. into exhaust channels. Cooling conduits are provided so that the air passes over the conduits which are arranged perpendicular through the walls defining the channels. An example of such a regenerative heat exchanger is disclosed in U.S. Pat. No. 2,128,641 to Folsom, which discloses a dehumidifier in which the walls between the channels serve as the heat exchange surface for the air as it passes through the intake channels, over the cooling conduits, and then around the channel walls into the exhaust channels and back over the cooling conduits. The air is then exhausted back into the atmosphere through exhaust ports located adjacent to the intake ports at the first end of the unit.
U.S. Pat. No. 4,761,966 to Stark teaches cooling and reheating for dehumidification, as well as an air temperature and water temperature control system for high humidity locations. U.S. Pat. No. 2,093,968 to Kettering provides regenerative heat exchange with an integral force fan fixed within the airstream and within the confines of the device. U.S. Pat. No. 4,517,810 to Foley et al. teaches regenerative heat exchange using a "run-around loop". Canadian Patent No. 470,100 teaches the use of a corrugated plate in a heat exchange element. German Patent No. 2,400,734 teaches non-continuous corrugated separators in a counterflowing heat exchanger, while U.S. Pat. No. 3,669,186 to Schauls teaches a plate type heat exchanger having a corrugated fin fluid distributor.
In the prior art heat exchangers, there is a required large plenum space to convey the intake air to a cooling coil or to convey exhaust air leaving the cooling coil to the final pass through the regenerative heat exchanger. The large plenum space in the prior art thus could be disposed either upstream of the cooling coil or downstream of the cooling coil. Accordingly, prior art heat exchangers required a large area for installation, and also required an excessive amount of energy to force the air through the heat exchanger.
The novel heat exchanger for dehumidification and air conditioning of the present invention obviates the disadvantages associated with the prior art, by providing a unitary structure which provides for both dehumidification and air conditioning by controlling the airflow through the device. The apparatus of the present invention provides a regenerative heat exchanger with at least one cooling conduit which is associated with the heat exchanger walls defining the channels within the device. The heat exchanger walls terminate at a position adjacent a closed end of the apparatus, which defines a small plenum chamber to redirect the air 180.degree. from the intake channels into the exhaust channels, to exit at the exhaust ports. The heat exchanger of the present invention also includes means for enhancing the regenerative heat exchanging function of the unit, thus providing a more cost efficient and compact device for installation in buildings, homes, etc.